National Yield Trends

Abstract Background Overviews often identify and synthesise a large number of systematic reviews on the same topic, which is likely to lead to overlap (i.e. duplication) in primary studies across the reviews. Using a primary study result multiple times in the same analysis overstates its sample size and number of events, falsely leading to greater precision in the analysis. This paper aims to: (a) describe types of overlapping data that arise from the same primary studies reported across multiple reviews, (b) describe methods to identify and explain overlap of primary study data, and (c) present six case studies illustrating different approaches to manage overlap. Methods We first updated the search in PubMed for methods from the MOoR framework relating to overlap of primary studies. One author screened the studies titles and abstracts, and any full-text articles retrieved, extracted methods data relating to overlap of primary studies and mapped it to the overlap methods from the MOoR framework. We also describe six case studies as examples of overviews that use specific overlap methods across the steps in the conduct of an overview. For each case study, we discuss potential methodological implications in terms of limitations, efficiency, usability, and resource use. Results Nine methods studies were found and mapped to the methods identified by the MOoR framework to address overlap. Overlap methods were mapped across four steps in the conduct of an overview – the eligibility criteria step, the data extraction step, the assessment of risk of bias step, and the synthesis step. Our overview case studies used multiple methods to reduce overlap at different steps in the conduct of an overview. Conclusions Our study underlines that there is currently no standard methodological approach to deal with overlap in primary studies across reviews. The level of complexity when dealing with overlap can vary depending on the yield, trends and patterns of the included literature and the scope of the overview question. Choosing a method might be dependent on the number of included reviews and their primary studies. Gaps in evaluation of methods to address overlap were found and further investigation in this area is needed.

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Residual Stresses Assessment in Coated Materials: Complementarity between Neutron and X-Ray Techniques

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.465.259 ◽

2011 ◽

Vol 465 ◽

pp. 259-262 ◽

Cited By ~ 1

Author(s):

M. Rogante ◽

Pavol Mikula ◽

Miroslav Vrána

Keyword(s):

Mechanical Tests ◽

Substantial Contribution ◽

Hole Drilling ◽

X Ray Diffraction ◽

Interface Area ◽

X Ray ◽

Coated Materials ◽

Coating Delamination ◽

Yield Trends ◽

Xrd Techniques

The residual stress (RS) status induced in the substrate of coated materials by the coating process plays frequently a major role in lending the component’s characteristics. RS assessment can give, thus, a substantial contribution in justifying different cases of failure or else bad performance of coated components due to e.g. the coating delamination or to other occurrences which are not simply interpretable via the conventional mechanical tests or microstructure analyses. The adoption of both neutron diffraction (ND) and X-ray diffraction (XRD) techniques has revealed its usefulness in assessing the RS values in proximity of the coating interface area, respectively, without any layer removal or hole drilling at the extreme surface. In this paper, some real cases of RS determination in coated materials by using these techniques and exploiting their complementarity are described. ND, in particular, is very suitable for crucial applications, where a much different stress situation than that assessed by XRD could be present at some depth below the surface. The results achieved can yield trends adoptable in monitoring of the coating features.

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Peculiarly pleasant weather for US maize

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1808035115 ◽

2018 ◽

Vol 115 (47) ◽

pp. 11935-11940 ◽

Cited By ~ 29

Author(s):

Ethan E. Butler ◽

Nathaniel D. Mueller ◽

Peter Huybers

Keyword(s):

Climate Change ◽

Growing Season ◽

Crop Model ◽

World Population ◽

Growth Phases ◽

Climate Trends ◽

Historical Trends ◽

Yield Trends ◽

The Relationship ◽

Temperature Responses

Continuation of historical trends in crop yield are critical to meeting the demands of a growing and more affluent world population. Climate change may compromise our ability to meet these demands, but estimates vary widely, highlighting the importance of understanding historical interactions between yield and climate trends. The relationship between temperature and yield is nuanced, involving differential yield outcomes to warm (9−29 °C) and hot (>29 °C) temperatures and differing sensitivity across growth phases. Here, we use a crop model that resolves temperature responses according to magnitude and growth phase to show that US maize has benefited from weather shifts since 1981. Improvements are related to lengthening of the growing season and cooling of the hottest temperatures. Furthermore, current farmer cropping schedules are more beneficial in the climate of the last decade than they would have been in earlier decades, indicating statistically significant adaptation to a changing climate of 13 kg·ha−1· decade−1. All together, the better weather experienced by US maize accounts for 28% of the yield trends since 1981. Sustaining positive trends in yield depends on whether improvements in agricultural climate continue and the degree to which farmers adapt to future climates.

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Use of Box‐Cox Transformation Technique for Fitting Crop Yield Trends

Agronomy Journal ◽

10.2134/agronj1983.00021962007500020035x ◽

1983 ◽

Vol 75 (2) ◽

pp. 310-314 ◽

Cited By ~ 1

Author(s):

Kuang‐Hsing T. Lin ◽

Chung‐Liang Huang

Keyword(s):

Crop Yield ◽

Transformation Technique ◽

Yield Trends ◽

Box Cox Transformation

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A Multidiagnostic Intercomparison of Tropical-Width Time Series Using Reanalyses and Satellite Observations

Journal of Climate ◽

10.1175/jcli-d-11-00127.1 ◽

2012 ◽

Vol 25 (4) ◽

pp. 1061-1078 ◽

Cited By ~ 124

Author(s):

Sean M. Davis ◽

Karen H. Rosenlof

Keyword(s):

Longwave Radiation ◽

Hadley Cell ◽

Radiosonde Data ◽

Full Time ◽

Robust Detection ◽

Time Period ◽

Wide Range ◽

The Mean ◽

Yield Trends ◽

The Tropics

Abstract Poleward migration of the latitudinal edge of the tropics of 0.25°–3.0° decade−1 has been reported in several recent studies based on satellite and radiosonde data and reanalysis output covering the past ~30 yr. The goal of this paper is to identify the extent to which this large range of trends can be explained by the use of different data sources, time periods, and edge definitions, as well as how the widening varies as a function of hemisphere and season. Toward this end, a suite of tropical edge latitude diagnostics based on tropopause height, winds, precipitation–evaporation, and outgoing longwave radiation (OLR) are analyzed using several reanalyses and satellite datasets. These diagnostics include both previously used definitions and new definitions designed for more robust detection. The wide range of widening trends is shown to be primarily due to the use of different datasets and edge definitions and only secondarily due to varying start–end dates. This study also shows that the large trends (>~1° decade−1) previously reported in tropopause and OLR diagnostics are due to the use of subjective definitions based on absolute thresholds. Statistically significant Hadley cell expansion based on the mean meridional streamfunction of 1.0°–1.5° decade−1 is found in three of four reanalyses that cover the full time period (1979–2009), whereas other diagnostics yield trends of −0.5°–0.8° decade−1 that are mostly insignificant. There are indications of hemispheric and seasonal differences in the trends, but the differences are not statistically significant.

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YIELD TRENDS AND APPARENT NUTRIENT BALANCES IN INTENSIFIED AND DIVERSIFIED RICE-BASED CROPPING SYSTEMS

Experimental Agriculture ◽

10.1017/s001447979900201x ◽

1999 ◽

Vol 35 (2) ◽

pp. 181-199 ◽

Cited By ~ 1

Author(s):

S. R. PASCUA JR ◽

W. VENTURA ◽

E. O. AGUSTIN ◽

A. T. PADRE ◽

D. A. VALENCIA ◽

...

Keyword(s):

Rice Yield ◽

Cropping Systems ◽

Residual Effect ◽

Sweet Pepper ◽

First Year ◽

Wet Season ◽

Crop Residue Incorporation ◽

Yield Trends ◽

Term Field

A long-term field trial was conducted to determine yield trends in relation to nutrient uptake and efficiency in different rice-based cropping systems. The cropping systems had a significant effect on wet season rice yield when residues were not recycled but had no effect otherwise. Rice yield decreased after the first year of crop residue incorporation but increased every year thereafter. Rice yield was significantly affected by residual nutrients applied to dry season crops. The highest residual effect was observed in tomato and sweet pepper to which the highest nitrogen (N), phosphorus (P) and potassium (K) rates were applied. Maize, sweet pepper, and tomato responded well to NPK application, garlic had a low response and mungbean had no response. A relay crop served as a catch crop for excess nutrients and as shade to minimize sunscald effects for tomato and sweet pepper fruits.

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Long-term effects of manure application on grain yield under different cropping systems and ecological conditions in China

The Journal of Agricultural Science ◽

10.1017/s0021859608008265 ◽

2008 ◽

Vol 147 (1) ◽

pp. 31-42 ◽

Cited By ~ 34

Author(s):

H. ZHANG ◽

M. XU ◽

F. ZHANG

Keyword(s):

Grain Yield ◽

Cropping Systems ◽

Long Term Effects ◽

Manure Application ◽

Organic C ◽

Wide Range ◽

Long Term Experiments ◽

Continuous Maize ◽

Yield Trends

SUMMARYRice (Oryza sativaL.), wheat (Triticum aestivumL.) and maize (Zea maysL.) are the main crops grown in China. Applying organic manures is an important practice in sustaining soil fertility and agricultural productivity in these cropping systems. The current paper presents the effects of manure application on grain yields in nine long-term experiments that consist of one continuous maize, four wheat–maize and four rice-based cropping systems across a wide range of agro-ecological regions in China. The study shows that regular manure application can increase soil organic carbon (SOC) and grain yield across all the sites. Overall, regular use of manure results in larger increases in SOC in the maize and wheat–maize systems than in the rice-based systems. Application of manure tends to increase the grain yield in the maize and wheat–maize systems during the final years, but increases the grain yield in the rice-based systems during the initial years of the long-term experiments. There is only one site that shows significant improvement in the yield trend in association with the application of manure. The effects of manure on yield trends are probably determined by the initial yield and/or the ‘organic C effect’ that may cause gradual improvements in SOC and soil physical properties.

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